Northwest Michigan fruit regional report – May 7, 2013

Warm and dry temperatures have accelerated tree growth across northwest Michigan.

The region has had a string of warm and dry days that feel more summer-like than spring. These temperatures have been a welcome change after a long winter, but the pace of tree growth has changed dramatically over the past week. On April 26, we were at silver tip in most varieties of apples at the Northwest Michigan Horticultural Research Center (NWMHRC), but just over a week later we are in tight cluster – things are simply moving fast and growers are working hard to keep up with this pace.

We have also jumped in our growing degree day accumulations, particularly base 50, as daytime temperatures have hovered in the low to mid-70s. We have accumulated 114 GDD base 50, which is just behind our 20-plus-year average of 125 GDD base 50, which is a marked change from last week where we were over one to two weeks behind normal. Obviously, we have also accumulated GDD base 42, and over this past week we are at 225 GDD base 42. We have not received much rain the past week, and we recorded 0.14 inches at the NWMHRC. Despite the good soil moisture to start the year, the first 4 to 5 inches of the soil are dry.

The trap line has been set at the NWMHRC this week, and we will be monitoring this line weekly or bi-weekly.

Apples. Growers are busy with spring tasks and sprayers have been out of the barn for over a week. Rain is in the forecast for Thursday of this week (May 9), and covering for apple scab is a priority. With all of the increased growth, keeping new tissue covered for scab is critical. Most growers will also add a mildewcide for powdery mildew for the cover as recommended by Michigan State University Extension.

Rosy apple aphids are the main insect that will need to be controlled at the upcoming pink spray. Mating disruption should be put up in orchards prior to bloom.

Cherries. We have observed white bud in sweet cherries, and if temperatures remain warm, we could be into bloom by the weekend. American brown rot is a concern, and we recommend using Rovral for bloom sprays to save the SI’s, primarily Indar for American brown rot control as we approach harvest. Retain, which is now labeled in cherries, should go on at early bloom to increase fruit set in shy-bearing varieties or if we run into poor pollinating weather.

In tart cherries, European brown rot applications need to be applied beginning at popcorn and again a week later. This disease is more of a problem in cool and wet weather, which has not been typical this spring, but there are some orchards where this disease is an annual issue. Also, this disease is more problematic in Balatons than Montmorency, so if the weather changes or an orchard is in a prime European brown rot site, Indar is the material of choice and should be applied at the above timings to control this disease.

Wine grapes. Recent warmer weather has brought many cultivars to the early bud swell stage. Bud development varies greatly from vine-to-vine and even within vines in the research vineyard. We would greatly .(JavaScript must be enabled to view this email address) on bud development uniformity in commercial vineyards.

No significant insect activity has been seen to this point, and the only species to be on the lookout for now are climbing cutworms and grape flea beetles. Grape flea beetles can often be found on wild vines in our area, so there is a possibility for it to become a pest. We are still in the time period for effective dormant applications against powdery mildew.

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